1.
Acid
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An acid is a molecule or ion capable of donating a hydron, or, alternatively, capable of forming a covalent bond with an electron pair. The first category of acids is the donors or Brønsted acids. In the special case of solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents, acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals to form salts. The word acid is derived from the Latin acidus/acēre meaning sour, an aqueous solution of an acid has a pH less than 7 and is colloquially also referred to as acid, while the strict definition refers only to the solute. A lower pH means a higher acidity, and thus a higher concentration of hydrogen ions in the solution. Chemicals or substances having the property of an acid are said to be acidic, common aqueous acids include hydrochloric acid, acetic acid, sulfuric acid, and citric acid. As these examples show, acids can be solutions or pure substances, strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid. The second category of acids are Lewis acids, which form a covalent bond with an electron pair, however, hydrogen chloride, acetic acid, and most other Brønsted-Lowry acids cannot form a covalent bond with an electron pair and are therefore not Lewis acids. Conversely, many Lewis acids are not Arrhenius or Brønsted-Lowry acids, in modern terminology, an acid is implicitly a Brønsted acid and not a Lewis acid, since chemists almost always refer to a Lewis acid explicitly as a Lewis acid. Modern definitions are concerned with the chemical reactions common to all acids. Most acids encountered in life are aqueous solutions, or can be dissolved in water, so the Arrhenius. The Brønsted-Lowry definition is the most widely used definition, unless otherwise specified, hydronium ions are acids according to all three definitions. Interestingly, although alcohols and amines can be Brønsted-Lowry acids, they can function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms. The Swedish chemist Svante Arrhenius attributed the properties of acidity to hydrogen ions or protons in 1884, an Arrhenius acid is a substance that, when added to water, increases the concentration of H+ ions in the water. Thus, an Arrhenius acid can also be described as a substance that increases the concentration of ions when added to water. Examples include molecular substances such as HCl and acetic acid, an Arrhenius base, on the other hand, is a substance which increases the concentration of hydroxide ions when dissolved in water. Thus, an Arrhenius acid could also be said to be one that decreases hydroxide concentration, in an acidic solution, the concentration of hydronium ions is greater than 10−7 moles per liter
2.
Etching
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Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio in the metal. In modern manufacturing, other chemicals may be used on other types of material, as a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today. In a number of variants such as microfabrication etching and photochemical milling it is a crucial technique in much modern technology. In traditional pure etching, a plate is covered with a waxy ground which is resistant to acid. The artist then scratches off the ground with an etching needle where he or she wants a line to appear in the finished piece. The échoppe, a tool with an oval section, is also used for swelling lines. The plate is dipped in a bath of acid, technically called the mordant or etchant. The acid bites into the metal where it is exposed, leaving behind lines sunk into the plate, the remaining ground is then cleaned off the plate. The plate is inked all over, and then the ink wiped off the surface, the plate is then put through a high-pressure printing press together with a sheet of paper. The paper picks up the ink from the lines, making a print. The process can be repeated many times, typically several hundred impressions could be printed before the shows much sign of wear. The work on the plate can also be added to by repeating the whole process, Etching has often been combined with other intaglio techniques such as engraving or aquatint. The process as applied to printmaking is believed to have been invented by Daniel Hopfer of Augsburg, Hopfer was a craftsman who decorated armour in this way, and applied the method to printmaking, using iron plates. Apart from his prints, there are two examples of his work on armour, a shield from 1536 now in the Real Armeria of Madrid. The switch to copper plates was made in Italy. On the other hand, the handling of the ground and acid need skill and experience, prior to 1100 AD, the New World Hohokam independently utilized the technique of acid etching in marine shell designs. Jacques Callot from Nancy in Lorraine made important technical advances in etching technique and he developed the échoppe, a type of etching-needle with a slanting oval section at the end, which enabled etchers to create a swelling line, as engravers were able to do. Callot also appears to have responsible for an improved, harder, recipe for the etching ground
3.
Carbon steel
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The term carbon steel may also be used in reference to steel which is not stainless steel, in this use carbon steel may include alloy steels. As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating, however, regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the carbon content lowers the melting point. Mild steel, also known as steel and Low carbon steel. It is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications, mild steel contains approximately 0. 05–0. 25% carbon making it malleable and ductile. Mild steel has a low tensile strength, but it is cheap and easy to form. It is often used large quantities of steel are needed. The density of steel is approximately 7.85 g/cm3. Low-carbon steels suffer from yield-point runout where the material has two yield points, the first yield point is higher than the second and the yield drops dramatically after the upper yield point. If a low-carbon steel is only stressed to some point between the upper and lower yield point then the surface develop Lüder bands, low-carbon steels contain less carbon than other steels and are easier to cold-form, making them easier to handle. Carbon steels which can successfully undergo heat-treatment have a content in the range of 0. 30–1. 70% by weight. Trace impurities of other elements can have a significant effect on the quality of the resulting steel. Trace amounts of sulfur in particular make the steel red-short, that is, brittle, low-alloy carbon steel, such as A36 grade, contains about 0. 05% sulfur and melts around 1, 426–1,538 °C. Manganese is often added to improve the hardenability of low-carbon steels and these additions turn the material into a low-alloy steel by some definitions, but AISIs definition of carbon steel allows up to 1. 65% manganese by weight. Carbon steel is broken down into four classes based on content,0.05 to 0. 25% carbon content. Balances ductility and strength and has good resistance, used for large parts, forging. Very strong, used for springs, swords, and high-strength wires, steels that can be tempered to great hardness. Used for special purposes like knives, axles or punches, most steels with more than 2. 5% carbon content are made using powder metallurgy
4.
Alloy steel
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Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1. 0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups, low-alloy steels and high-alloy steels, the difference between the two is somewhat arbitrary, Smith and Hashemi define the difference at 4. 0%, while Degarmo, et al. define it at 8. 0%. Most commonly, the alloy steel refers to low-alloy steels. Strictly speaking, every steel is an alloy, but not all steels are called alloy steels, the simplest steels are iron alloyed with carbon. However, the alloy steel is the standard term referring to steels with other alloying elements added deliberately in addition to the carbon. Common alloyants include manganese, nickel, chromium, molybdenum, vanadium, silicon, less common alloyants include aluminum, cobalt, copper, cerium, niobium, titanium, tungsten, tin, zinc, lead, and zirconium. The following is a range of improved properties in alloy steels, strength, hardness, toughness, wear resistance, corrosion resistance, hardenability, to achieve some of these improved properties the metal may require heat treating. Some of these uses in exotic and highly-demanding applications, such as in the turbine blades of jet engines, in spacecraft. Because of the properties of iron, some steel alloys find important applications where their responses to magnetism are very important, including in electric motors. A few common low alloy steels are, D6AC 300M 256A Alloying elements are added to certain properties in the material. Manganese, silicon, or aluminum are added during the process to remove dissolved oxygen, sulfur. Manganese, silicon, nickel, and copper are added to increase strength by forming solid solutions in ferrite, chromium, vanadium, molybdenum, and tungsten increase strength by forming second-phase carbides. Nickel and copper improve corrosion resistance in small quantities, zirconium, cerium, and calcium increase toughness by controlling the shape of inclusions. Sulfur lead, bismuth, selenium, and tellurium increase machinability, the alloying elements tend to form either solid solutions or compounds or carbides. Nickel is very soluble in ferrite, therefore, it forms compounds, aluminium dissolves in the ferrite and forms the compounds Al2O3 and AlN. Silicon is also very soluble and usually forms the compound SiO2•MxOy, manganese mostly dissolves in ferrite forming the compounds MnS, MnO•SiO2, but will also form carbides in the form of 3C. Chromium forms partitions between the ferrite and carbide phases in steel, forming C, Cr7C3, and Cr23C6, the type of carbide that chromium forms depends on the amount of carbon and other types of alloying elements present. Tungsten and molybdenum form carbides if there is enough carbon and an absence of stronger carbide forming elements, they form the carbides W2C and Mo2C, vanadium, titanium, and niobium are strong carbide forming elements, forming vanadium carbide, titanium carbide, and niobium carbide, respectively
5.
Nickel
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Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a golden tinge. Nickel belongs to the metals and is hard and ductile. Meteoric nickel is found in combination with iron, a reflection of the origin of elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earths inner core, use of nickel has been traced as far back as 3500 BCE. Nickel was first isolated and classified as an element in 1751 by Axel Fredrik Cronstedt. The elements name comes from a mischievous sprite of German miner mythology, Nickel, an economically important source of nickel is the iron ore limonite, which often contains 1–2% nickel. Nickels other important ore minerals include garnierite, and pentlandite, major production sites include the Sudbury region in Canada, New Caledonia in the Pacific, and Norilsk in Russia. Nickel is slowly oxidized by air at room temperature and is considered corrosion-resistant, historically, it has been used for plating iron and brass, coating chemistry equipment, and manufacturing certain alloys that retain a high silvery polish, such as German silver. About 6% of world production is still used for corrosion-resistant pure-nickel plating. Nickel-plated objects sometimes provoke nickel allergy, Nickel has been widely used in coins, though its rising price has led to some replacement with cheaper metals in recent years. Nickel is one of four elements that are ferromagnetic around room temperature, alnico permanent magnets based partly on nickel are of intermediate strength between iron-based permanent magnets and rare-earth magnets. The metal is valuable in modern times chiefly in alloys, about 60% of world production is used in nickel-steels, other common alloys and some new superalloys comprise most of the remainder of world nickel use, with chemical uses for nickel compounds consuming less than 3% of production. As a compound, nickel has a number of chemical manufacturing uses. Nickel is a nutrient for some microorganisms and plants that have enzymes with nickel as an active site. Nickel is a metal with a slight golden tinge that takes a high polish. It is one of four elements that are magnetic at or near room temperature. Its Curie temperature is 355 °C, meaning that bulk nickel is non-magnetic above this temperature, the unit cell of nickel is a face-centered cube with the lattice parameter of 0.352 nm, giving an atomic radius of 0.124 nm
6.
Sword
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A sword is a long bladed weapon intended for slashing or thrusting. The precise definition of the term varies with the epoch or the geographical region under consideration. A sword consists of a blade attached to a hilt. The blade can be straight or curved, thrusting swords have a pointed tip on the blade, and tend to be straighter, slashing swords have sharpened cutting edge on one or both sides of the blade, and are more likely to be curved. Many swords are designed for thrusting and slashing. Historically, the sword developed in the Bronze Age, evolving from the dagger, the later Iron Age sword remained fairly short and without a crossguard. The word sword continues the Old English, sweord, the use of a sword is known as swordsmanship or as fencing. In the Early Modern period, western sword design diverged into two forms, the thrusting swords and the sabers. The thrusting swords such as the rapier and eventually the smallsword were designed to impale their targets quickly and their long and straight yet light and well balanced design made them highly maneuverable and deadly in a duel but fairly ineffective when used in a slashing or chopping motion. A well aimed lunge and thrust could end a fight in seconds with just the swords point, the saber and similar blades such as the cutlass were built more heavily and were more typically used in warfare. Built for slashing and chopping at multiple enemies, often from horseback, most sabers also had sharp points and double edged blades, making them capable of piercing soldier after soldier in a cavalry charge. Sabers continued to see use until the early 20th century. The US Navy kept tens of thousands of sturdy cutlasses in their armory well into World War II, non-European weapons called sword include single-edged weapons such as the Middle Eastern scimitar, the Chinese dao and the related Japanese katana. The Chinese jian is an example of a non-European double-edged sword, the first weapons that can be described as swords date to around 3300 BC. They have been found in Arslantepe, Turkey, are made from arsenical bronze, some of them are inlaid with silver. The sword developed from the dagger when the construction of longer blades became possible, from the late 3rd millennium BC in the Middle East, first in arsenic copper, then in tin-bronze. Blades longer than 60 cm were rare and not practical until the late Bronze Age because the strength of bronze is relatively low. These are the type A swords of the Aegean Bronze Age, one of the most important, and longest-lasting, types swords of the European Bronze Age was the Naue II type, also known as Griffzungenschwert
7.
Knife
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A knife is a tool with a cutting edge or blade, hand-held or otherwise, with most having a handle. Some types of knives are used as utensils, including knives used at the dining table, many types of knives are used as tools, such as the utility knife carried by soldiers, the pocket knife carried by hikers and the hunting knife used by hunters. Knives are also used as a traditional or religious implement, such as the kirpan, some types of knives are used as weapons, such as daggers or switchblades. Some types of knives are used as sports equipment, Knives are also used in agriculture, food harvesting etc. the sickle, the scythe and even the combine harvester are knives. Knife-like tools were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools. Originally made of rock, bone, flint, and obsidian, knives have evolved in construction as technology has, with blades being made from bronze, copper, iron, steel, ceramics, many cultures have their unique version of the knife. Due to its role as humankinds first tool, certain cultures have attached spiritual, most modern-day knives follow either a fixed-blade or a folding construction style, with blade patterns and styles as varied as their makers and countries of origin. The word knife possibly descends from an old Norse word knifr for blade, single-edged knives may have a reverse edge or false edge occupying a section of the spine. These edges are serrated and are used to further enhance function. The handle, used to grip and manipulate the blade safely, may include a tang, Knives are made with partial tangs or full tangs. The handle may include a bolster, a piece of heavy material situated at the front or rear of the handle, the bolster, as its name suggests, is used to mechanically strengthen the knife. Knife blades can be manufactured from a variety of materials, each of which has advantages and disadvantages, carbon steel, an alloy of iron and carbon, can be very sharp. It holds its edge well, and remains easy to sharpen, stainless steel is an alloy of iron, chromium, possibly nickel, and molybdenum, with only a small amount of carbon. It is not able to quite as sharp an edge as carbon steel. High carbon stainless steel is steel with a higher amount of carbon, intended to incorporate the better attributes of carbon steel. High carbon stainless steel blades do not discolor or stain, laminate blades use multiple metals to create a layered sandwich, combining the attributes of both. For example, a harder, more brittle steel may be sandwiched between a layer of softer, tougher, stainless steel to reduce vulnerability to corrosion. In this case, however, the part most affected by corrosion, pattern-welding is similar to laminate construction
8.
Metal
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A metal is a material that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally malleable—that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible and ductile, about 91 of the 118 elements in the periodic table are metals, the others are nonmetals or metalloids. Some elements appear in both metallic and non-metallic forms, astrophysicists use the term metal to collectively describe all elements other than hydrogen and helium, the simplest two, in a star. The star fuses smaller atoms, mostly hydrogen and helium, to larger ones over its lifetime. In that sense, the metallicity of an object is the proportion of its matter made up of all chemical elements. Many elements and compounds that are not normally classified as metals become metallic under high pressures, the atoms of metallic substances are typically arranged in one of three common crystal structures, namely body-centered cubic, face-centered cubic, and hexagonal close-packed. In bcc, each atom is positioned at the center of a cube of eight others, in fcc and hcp, each atom is surrounded by twelve others, but the stacking of the layers differs. Some metals adopt different structures depending on the temperature, atoms of metals readily lose their outer shell electrons, resulting in a free flowing cloud of electrons within their otherwise solid arrangement. This provides the ability of metallic substances to easily transmit heat, while this flow of electrons occurs, the solid characteristic of the metal is produced by electrostatic interactions between each atom and the electron cloud. This type of bond is called a metallic bond, Metals are usually inclined to form cations through electron loss, reacting with oxygen in the air to form oxides over various timescales. Examples,4 Na + O2 →2 Na2O2 Ca + O2 →2 CaO4 Al +3 O2 →2 Al2O3, the transition metals are slower to oxidize because they form a passivating layer of oxide that protects the interior. Others, like palladium, platinum and gold, do not react with the atmosphere at all, some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades. The oxides of metals are generally basic, as opposed to those of nonmetals, exceptions are largely oxides with very high oxidation states such as CrO3, Mn2O7, and OsO4, which have strictly acidic reactions. Painting, anodizing or plating metals are good ways to prevent their corrosion, however, a more reactive metal in the electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two form an electrochemical cell, and if the coating is less reactive than the coatee. Metals in general have high conductivity, high thermal conductivity. Typically they are malleable and ductile, deforming under stress without cleaving, in terms of optical properties, metals are shiny and lustrous. Sheets of metal beyond a few micrometres in thickness appear opaque, although most metals have higher densities than most nonmetals, there is wide variation in their densities, lithium being the least dense solid element and osmium the densest
9.
Damascus steel
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Damascus steel was a type of steel used for manufacturing sword blades in the Near East made with wootz steel. These swords are characterized by patterns of banding and mottling reminiscent of flowing water. Such blades were reputed to be tough, resistant to shattering and capable of being honed to a sharp, the steel is named after Damascus, the capital city of Syria. It may either refer to swords made or sold in Damascus directly, or it may just refer to the aspect of the typical patterns, the original method of producing Damascus steel is not known. Modern attempts to duplicate the metal have not been successful due to differences in raw materials. Several individuals in modern times have claimed that they have rediscovered the methods by which the original Damascus steel was produced. The reputation and history of Damascus steel has given rise to many legends, a research team in Germany published a report in 2006 revealing nanowires and carbon nanotubes in a blade forged from Damascus steel. These ingots would then be further forged and worked into Damascus steel blades, research now shows that carbon nanotubes can be derived from plant fibers, suggesting how the nanotubes were formed in the steel. Some experts expect to discover such nanotubes in more relics as they are analyzed more closely, Damascus blades were manufactured in the Near East from ingots of wootz steel that were imported from India, as well as Sri Lanka. Archaeological evidence suggests that the steel process started in the present-day Tamil Nadu before the start of Common Era. The Arabs introduced the Indian wootz steel to Damascus, where a weapons industry thrived, from the 3rd century to the 17th century, India was shipping steel ingots to the Middle East. Production of these patterned swords gradually declined, ceasing by around 1750, the original Damascus steel or wootz was imported from India to Damascus, where bladesmiths learned how to forge them into swords. The technique for controlled thermal cycling after the initial forging at a specific temperature could also have been lost, recreating Damascus steel is a subfield of experimental archaeology. Many have attempted to discover or reverse-engineer the process by which it was made, pattern-welded steel has been referred to as Damascus steel since 1973 when Bladesmith William F. Moran unveiled his Damascus knives at the Knifemakers Guild Show. The patterns vary depending on how the works the billet. The billet is drawn out and folded until the number of layers are formed. In order to attain a Master Smith rating with the American Bladesmith Society that Moran founded, J. D. Verhoeven and A. H. Pendray published an article on their attempts to reproduce the elemental, structural, and visual characteristics of Damascus steel. The wootz was in a soft, annealed state, with a grain structure, however, Verhoeven and Pendray discovered that in samples of true Damascus steel, the Damascene pattern could be recovered by aging at a moderate temperature
